Among pediatric patients with hemophilia A with factor VIII (FVIII) inhibitors, emicizumab appears to be effective for preventing bleeding, regardless of evaluated dosage, according to a 1-year analysis presented at the 2022 American Society of Pediatric Hematology/Oncology Conference.

Previous research has shown that emicizumab bridges FX and activated FIX, potentially making up for loss of FVIII function. The phase 3 HAVEN 2 study ( Identifier: NCT02795767) evaluated whether emicizumab prophylaxis is safe and efficacious among pediatric patients with hemophilia A and FVIII inhibitors.

The primary analysis from HAVEN 2 yielded data for the weekly dosing arm, but data were not, at that point, analyzed for the emicizumab 3 mg/kg every 2 week (Q2W) and emicizumab 6 mg/kg every 4 week (Q4W) arms. In the presented poster, researchers presented a 52-week safety and efficacy analysis of the Q2W and Q4W arms from HAVEN 2.

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A total of 10 patients were enrolled to each of the Q2W and Q4W groups. By November 2020, the median emicizumab exposure was 67.1 weeks in the Q2W arm, and 66.6 weeks in the Q4W arm. In the Q2W vs Q4W arms, the median age was 8 vs 9 years, respectively, 100% vs 100% of patients were male sex, 100% vs 100% of patients had severe hemophilia at baseline, and the median number of bleeds in the 24 weeks prior to study entry was 5 vs 6.

Analysis showed that, in the Q2W and Q4W groups, the annualized bleeding rates were 0.2 (95% CI, 0.06-0.54) and 1.8 (95% CI, 0.32-10.59), respectively, both of which were consistent with previous HAVEN 2 data from the weekly dosing arm. A total of 90% of patients in both arms experienced 0 to 3 bleeds over the analyzed period.

There was 1 patient in the Q2W arm and 3 patients in the Q4W arm who had a serious adverse event, 1 of which led to discontinuation in the latter group. No adverse events were fatal, and no new safety signals were observed compared with the primary HAVEN 2 analysis.

Disclosure: The study author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

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Young G, Sidonio Jr R, Oldenburg J, et al. Efficacy/safety in children on 2/4-weekly emicizumab prophylaxis: 52-week outcomes in HAVEN 2. Poster presented at: 2022 American Society of Pediatric Hematology/Oncology (ASPHO) Conference; May 4-7, 2022. Abstract 010.